1. Window Regulator Motor: The most common culprit. The motor might be weak or failing. When going down, gravity assists, but going up requires more power.
* Test: Try manually lifting the window. If it feels excessively heavy or resists movement significantly, the motor is likely the problem. Sometimes you can hear a grinding or clicking sound from the motor which also points to failure.
2. Window Regulator Cable/Mechanism: The cables that connect the motor to the window can become frayed, broken, or dislodged. This is especially common in older vehicles.
* Test: Inspect the window mechanism if possible. Accessing this usually requires removing the door panel (plenty of online guides show you how). Look for broken cables, dislodged parts, or anything that appears bent or damaged.
3. Switch (Even Though It Seems Fine): While the switch moves, it's possible an internal component is failing. It might be sending the signal to go down but not the signal to go up. This is less likely given that the master control also doesn't work, but it's still a possibility.
* Test: If you have access to a multimeter, you could try testing the voltage at the switch's output when trying to raise the window. (This requires electrical knowledge and caution).
4. Wiring Harness (Between Switch and Regulator): The wiring harness connecting the switch to the window regulator can be damaged or corroded. This is more likely if the problem is intermittent.
* Test: Carefully inspect the wiring harness for any breaks, frayed wires, or corrosion, especially near the door hinges where wires are often stressed.
5. Poor Ground Connection: A faulty ground connection can prevent the motor from receiving the proper electrical signal to raise the window.
* Test: Trace the ground wire for the window regulator. Look for corrosion or loose connections. Clean the connection if needed and make sure it's secure.
6. Body Control Module (BCM) - Less Likely: In some rare cases, a fault in the BCM (or other control module) could prevent the upward signal. This is usually accompanied by other electrical issues.
Troubleshooting Steps:
1. Start with the easiest: Check all connections and visually inspect the wiring again.
2. Access the window regulator: Remove the door panel to get a better look at the mechanism and cables. Plenty of YouTube videos show how to do this for a 2003 Pontiac Montana.
3. Test the motor (if accessible): Try applying power directly to the motor (if you are comfortable with electrical work and have the necessary knowledge and safety equipment), to verify it functions. Be extremely cautious doing this.
4. Replace the regulator: This is often the most practical solution, especially if the cables are damaged. They're relatively inexpensive and readily available online or at auto parts stores.
Important Note: Working with car electrical systems can be dangerous. If you are not comfortable working with electricity, take your vehicle to a qualified mechanic. Improper repairs can lead to further damage or injury.
